I think it means "she(the speaker) wasted time she had" but I amnot sure.

The full text is:

A week after the wedding I broke up with Nick—callously, I’m ashamed
to say. I never told him of my life before, never sketched for him the world
that had invaded and obliterated the one he and I had shared. I could have
explained. I could have said, “That place has a hold on me, which I may
never break.” That would have got to the heart of it. Instead I sank through
time. It was too late to confide in Nick, to take him with me wherever I was
going. So I said goodbye.